After over 8 years of battling various different GPs in wherever I happened to be living at the time (and in the meantime, self-medicating orally), I’ve finally been given the go ahead by the senior partner at my local practice to have a B12 injection.
However she said that as my blood test results showed me still being “in range”, albeit at the bottom end, then they wouldn’t be giving me loading doses. My B12 was 429 back in August this year but had been as low as 224 back in 2016 before supplementing orally
I’m not, quite sure of the logic being applied here ….. Surely I need loading devices as part of a normal course of treatment?
On a separate note would I be right in thinking that with the sub lingual methylcobalamin tablets I’ve been taking, only a tiny percentage of it (2%?) actually gets into my bloodstream?
Also, I’m confused about the storage mechanism. I’ve read that B12 is stored in the liver, long-term for use by the body when needed, but any excess is excreted in urine.
Is the purpose of loading devices to top up the storage reserves of B12 in the liver? In which case, surely the loading doses would be needed? Or have I misunderstood?
Written by
Edso57
To view profiles and participate in discussions please or .
Yes around 1-3% is estimated for passive absorption. I believe the idea behind the loading doses is to saturate the body with B12 to top up B12 reserves in the liver but B12 is also stored in the muscles (~30%). The problem in the case of PA is that the mechanism the body makes use of to re-absorb B12 when secreted by the liver is broken due to lack of intrinsic factor, so these reserves cannot be used in the same way they would be in someone without PA.
Loading doses might not be prescribed if your deficiency is not believed to be serious. Which is in my opinion, a very difficult judgement call. But most GP's seem to consider a serum B12 test to give them an infallible answer as to the presence of a B12 deficiency and the seriousness of the deficiency, neither of which are true IMO.
There is a helpline number that PAS members can ring.
PAS membership is separate to membership of this forum.
Should be some useful info in threads below.
Links to forum threads where I left detailed replies with lots of B12 deficiency info eg causes and symptoms, more UK B12 documents, B12 books, B12 films, B12 websites and B12 articles and a few hints on dealing with unhelpful GPs.
Some links may have details that could be upsetting.
Doctors are useless if just asked merely one of them and even can make worse some of unusual maladies . Mostly they don't get updated in ten years when it come to little known diseases by public. Because they don't have much time to do so. Everybody needs to get three or more doctors opinion and at the same time study articles and after a while can figure out what's wrong and by some practice learn the best way of treatment. Anyways loading dose is required as part of healing process. Peripheral nerves damage require lots of B12 if no specific target is available. In recent way of treatment after imaging damaged nerves now use an ultrasound device to send b12 to nerves damaged spot. But until dominance of such technics loading dose is mandatory
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
B12 loading doses feel terrible
No loading doses allowed 
B12 loading doses no difference
B12 loading doses and stomach pain; also 10mg melatonin OK to take on loading doses?
B12 Loading doses for months? MTHFR genetic defects.
